Hans Blix was director of the International Atomic Energy Agency (IAEA) from 1981 to 1997 and the chief United Nations arms inspector for Iraq from 2000 to 2003. He spoke from his home in Stockholm with NPQ in February.

NPQ | What do you make of the deal between North Korea and the five powers (the United States, Russia, Japan, China and South Korea) to move toward disarming the North's nuclear program?

Hans Blix | Of course, it is desirable and welcome. It demonstrates that the other option—war and regime change—was just not realistic in the case of North Korea. It has massive artillery aimed at Seoul. It is clear that the US, for quite some time, has tried not to inflame the situation.

The phased approach in negotiations—a step-by-step calibration of who gets what—is a sensible one. There will be many snags ahead as future negotiations go through the planned steps. It won't be easy. The North Koreans are cornered and will try to get the maximum leverage out of the missile and bomb tests they have already conducted. But this is an important first step.

NPQ | What changed finally to make this deal possible after years of seemingly endless negotiations?

Blix | The most important change, in my view, is that the US put on the table the ultimate promise of security guarantees and normalization of relations at the end of the process of disarmament. These were fundamental. The point the North Koreans always came back to in any negotiation was that the US had to give up its hostility.

In the end, what did North Korea see as the guarantee of its independence and the survival of its regime—the bomb or security guarantees? They must know that a bomb will only bring them more isolation and make their survival a frail affair.

Here, the multilateral approach of the five surrounding parties seems to have an advantage: It puts more pressure on North Korea to follow through, but it also makes North Korea believe more in security assurances against regime change from the US. The reliability and credibility of any assurances have been enhanced all around.

And, of course, now there are a lot of immediate carrots on the table, primarily the oil supplies North Korea badly needs in winter.

In general, the ongoing economic squeeze on North Korea has pressured it to make a deal—after all, North Koreans live at a miserably low level. But I'm not sure how much the recent sanctions imposed by the UN really matter. They are not so numerous. How much can holding back a few million from a Macao bank really matter? Also, the Chinese have made clear they will not inspect North Korean ships at sea.

NPQ | Having been a nuclear arms inspector in many places around the world, including North Korea, what hurdles lie ahead in fulfilling any agreement by the North to disarm?

Blix | First, North Korea has to make a declaration of all its nuclear sites that, by IAEA rules, must be "complete and correct." When the crisis first erupted in North Korea in the 1990s when I was head of the IAEA, we had concluded that the North Korean declaration was not "correct." The IAEA concluded they had more plutonium than they had declared because they had reprocessed on more than one occasion.

Will their declarations be correct this time? Are there other sites besides Yongbyon that will be open for inspection? I know there is another place where there is a 200-megawatt reactor under construction. I've been there. Are there sites for uranium enrichment, as the US claims, or not? What about uranium mines? I've been to one. How many others are there?

North Korea is a big country with lots of tunnels dug into the hills. What is in those tunnels? How confident can we be with what we know from satellite images alone?

What freedom of movement will IAEA inspectors have? Everyone remembers what a big issue that was in Iraq. In Iran today, where there is also a nuclear dispute, foreigners are all over the place. It is internationalized. North Korea is a closed country. That will make inspections by foreigners more difficult. We will have to be more wary of North Korea than Iran when it comes to inspections.

NPQ | How come a deal could be struck with the difficult North Koreans but not the internationalized Iranians?

Blix | First of all, there has been no mention at all of security guarantees in negotiations with Iran and the West. Maybe the Iranians are too proud to ask for it, but it has not been offered by the US for sure.

Second, there has been no talk about normalization of relations at the end of the process because the US has had no diplomatic relations since the embassy hostage crisis in 1979.

Another important difference—and this is central: The Europeans and Americans have insisted that Iran suspend uranium enrichment as a precondition before they will sit down in talks. With North Korea, the negotiations went on round after round even as it was producing more plutonium!

Iran has only enriched a tiny quantity of uranium. And it is fairly far away from a bomb, perhaps years. Yet North Korea tested a bomb and the talks went on anyway.

The West has painted itself into a corner on Iran. It should sit down and talk with Iran without preconditions. Why shouldn't an agreement like that with North Korea be possible with Iran?

NPQ | So the North Korean deal is a model for what could happen with Iran?

Blix | Absolutely. To proceed with Iran, the West should drop preconditions for starting talks and contemplate security guarantees. And if Iran is shown to be meddling in Iraq, that can be raised in talks as well. It's a legitimate subject.